The present invention relates to a reusable multicompartment thermal pack comprising a bag formed of a water-permeable fabric defining a plurality of laterally adjacent compartments, and a superabsorbent polymer disposed in the bag compartments.
Thermal packs that can be chilled or heated for use as cold and hot compresses, respectfully, are well known in the prior art. For example, the most widely used thermal packs in the prior art are hot water bottles or ice bags made of rubber or plastic material. However, the problem with such packs is that they generally tend to be cumbersome, weighty and are not particularly useful for travel.
Other typical thermal packs in the prior art contain water, gel or other ingredients that permit the packs to be chilled or heated, and then applied to the desired area. For example, Kelley, U.S. Pat. No. 4,865,012, issued Sep. 12, 1989, describes such a reusable thermal pack that comprises a mixture of water, salt, cellulose and flour sealed in a pliable bag, that can be chilled or heated as desired. Gordon, et al., U.S. Pat. No. 4,910,978, issued Mar. 27, 1990, describes a reusable thermal pack comprising a gel-like substance in a plastic bag containing a fabric outer layer. However, the problem with such packs is that because they always contain water or gelled material, they tend to be cumbersome, weighty and take up a great deal of storage space.
In addition to the aforementioned packs, other packs are known in the prior art. For example, Anderson, U.S. Pat. No. 5,150,707, issued Sep. 29, 1992, describes a hot/cold thermal pack that contains an absorbent package having a gel-forming synthetic resin in particulate form deposited on an adhesive-coated substrate disposed between a pair of fibrous non-woven porous filter layers and covered on the outside by a pair of paper-like plies of nonwoven porous absorbent material. However, when the Anderson pack is exposed to water, the adhesive coating dissolves thus rendering the Anderson pack non-reusable. In addition, the Anderson pack is complex to manufacture.
Lahey, et al., U.S. Pat. No. 4,780,117, issued Oct. 25, 1988, describes a time-release cooling pack having a first compartment containing solid reactant particles coated with a reaction delaying penetrable coating and a second compartment containing a liquid which reacts with the solid reactant in an endothermic reaction. However, like the Anderson pack, the Lahey pack is not reusable, and in addition, can only be used as a cold pack.
Cheney, et al., U.S. Pat. No. 5,391,198, issued Feb. 21, 1995, describes a hot/cold thermal compress that comprises a water porous fabric bag containing a dehydrated water soluble acrylic polymer and a thickening agent to enhance the water absorption of the polymer. However, because the Cheney compress utilizes a water soluble polymer, a portion of the polymer will invariably be released from the compress when in contact with water, resulting in an unpleasant feel to the user, and also limiting the useful life of the compress. In addition, the Cheney compress requires the use of a thickening agent to enhance the water absorption of the polymer. A variation of this pack is also described in Cheney, et al., U.S. Pat. No. 5,534,020, issued Jul. 9, 1996, where ammonium nitrate or calcium chloride replace the thickening agent, and a separate, enclosed bag of water is also included within the pack.
Zafiroglu, U.S. Pat. No. 4,897,297, issued Jan. 30, 1990, describes a compress that comprises two outer layers surrounding a particulate filling material made of 5-30% of a superabsorbent polymer and 70-95% of a diluent such as wood pulp. At least one of the outer layers is a water-permeable, elastic fabric. The Zafiroglu Patent, however, teaches that concentrations of superabsorbent polymer greater than 30% should be avoided because at such concentrations, the filling material does not wet uniformly, may even block after absorbing but a small about of water, and its water-holding capacity per unit weight starts diminishing with further increases in concentration.